Synchronous Operation Research Articles

High-Speed Image Analysis of the Rock Fracture Process under the Impact of Blasting

The purpose of this paper was to observe the generation, development, and extent impact of rock fissures under the blasting process; the failure process of rock under the gases expansion pressure. The latest high-speed camera, producing about 30,000 frames per second (each grid was 32 µs, and exposure time 4 µs), was used to capture the failure process of rock in blasting concrete specimens. The types of cracks and the rate of extended development in a quantitative way were recorded for observation, analysis, and verification of the failure mechanism of induced by blasting. The results showed that the gas expansion rate after blasting reached the maximum of about 200 µs and then gradually attenuated. As to the development rate of the fragmentation of rock after blasting, it reached the maximum of about 130 µs, and the attenuation then became gradual. It is concluded that high-speed photography provides meaningful scientific basis for study of the detonation theory of explosives, rock blasting fracture mechanism, analysis of blast effects, etc. Further improvement and research can be done on the control of the synchronous operation of blasting and photography, and the three-dimensional spatial analysis of the rock blasting process.

Efficient lock‐step synchronization in task‐parallel languages

SummaryMany modern task‐parallel languages allow the programmer to synchronize tasks using high‐level constructs like barriers, clocks, and phasers. While these high‐level synchronization primitives help the programmer express the program logic in a convenient manner, they also have their associated overheads. In this paper, we identify the sources of some of these overheads for task‐parallel languages like X10 that support lock‐step synchronization, and propose a mechanism to reduce these overheads.We first propose three desirable properties that an efficient runtime (for task‐parallel languages like X10, HJ, Chapel, and so on) should satisfy, to minimize the overheads during lock‐step synchronization. We use these properties to derive a scheme to called uClocks to improve the efficiency of X10 clocks; uClocks consists of an extension to X10 clocks and two related runtime optimizations. We prove that uClocks satisfies the proposed desirable properties. We have implemented uClocks for the X10 language+runtime and show that the resulting system leads to a geometric mean speedup of 5.36× on a 16‐core Intel system and 11.39× on a 64‐core AMD system, for benchmarks with a significant number of synchronization operations.

Reactive Power Synchronization Method for Voltage-Sourced Converters

There is a growing interest in the parallel operation of voltage source converters (VSCs) both in an isolated microgrid or connected to the utility grid. The most common solution in the literature for the paralellization of VSCs is the so-called droop control, which brings about a relationship between active power and frequency. In this paper, a different approach is proposed where reactive power is used instead of active power to ensure synchronous operation. Active and reactive power are independently controlled using a dq-frame representation based on the vector oriented control, which inherently provides current limitation capability. A detailed dynamic model of the system is used to demonstrate the relation between reactive power and frequency. Due to the intrinsic synchronizing mechanism, the proposed scheme can operate in both isolated and grid-connected modes. As opposed to droop control schemes, active power is not used for synchronization and thus synchronization is possible even if active power is not controllable. Simulation and experimental results, for a case study where a VSC is connected to a host grid, are presented to validate the proposal.

Анализ допустимости режима потери возбуждения синхронного генератора в условиях промышленной системы электроснабжения сложной конфигурации

Modern operating conditions of large industrial enterprises require the provision of high reliability of power supply to consumers while reducing the cost of the electricity consumed. These requirements are ensured by the widespread introduction of own sources of electrical energy. These include combined heat and power plants, gas turbines, gas pistons and steam and gas power plants. At the same time, there is a significant complication of the industrial network configuration and possible emergency modes. One of the emergency modes in such networks is the loss of excitation of the synchronous generator. The admissibility of such a regime is specified by regulatory documents. In this situation, the generator goes into asynchronous mode and consumes reactive power from the network. The purpose of this work is to identify the admissibility of the synchronous generator operation for a certain time in the asynchronous mode as a result of the loss of excitation. An algorithm has been developed to calculate the transient electromechanical process of a synchronous generator taking into account the loss of machine excitation. Investigations have been carried out for various operating modes of an industrial power plant taking into account the initial generator load using the KATRAN software. The calculation results allow determining the generator load by active power at which the synchronous generator can operate in the asynchronous mode without excitation.

Islanding and non-islanding disturbance detection in microgrid using optimized modes decomposition based robust random vector functional link network

This paper presents detection and classification of islanding and non-islanding disturbances in a PV based microgrid scenario. To design effective pattern recognition the microgrid is conditioned to operate in grid synchronous mode (i.e. according to IEEE 1547) as well as islanding mode. Various non-islanding disturbances such as sag, swell, harmonics, load switching along with islanding event (during grid synchronous operation, according to UL 1741, section 46) are generated in the microgrid and the non-stationary voltage signal samples for each event has been extracted. To cope with the requirement for the dynamic detection threshold, parameter adaptive Variational Mode Decomposition (PAVMD) with Robust Regularized Random Vector Functional Link Network (RRVFLN) has been introduced in this paper. These extracted waveforms are subjected to the proposed novel PAVMD algorithm where firefly algorithm has been used for parameter optimization. Distinguishable features are extracted from the output of the proposed method PAVMD. Applicability of PAVMD with RRVFLN has been tested for different disturbances in grid-connected mode as well as islanding mode condition which is completely a new contribution to the existing literature. The proposed algorithm has been tested for noisy condition as well. Classification accuracy achieved with the proposed method is satisfactory and acceptable.

DEPLEST: A blockchain-based privacy-preserving distributed database toward user behaviors in social networks

Social networks record a significant amount of user behavior data every day. By analyzing this behavior data, companies or attackers use it for marketing or more questionable purposes. We propose a blockchain-based model to protect the privacy of users’ data in such big data environments. Traditional blockchain methods require too many resources for this task, so we propose a model that secures sensitive user information in a distributed blockchain and passes nonsensitive information through to the primary system in order to manage the blockchain size. Our DEPLEST algorithm performs these synchronization operations to keep local database storage and computational capacity within the limits of individual users’ devices. We also propose a consensus protocol for blockchain ledger maintenance that runs well on typical client systems and prove that this protocol has excellent Byzantine fault tolerance (BFT). Our experimental results show that DEPLEST meets the architectural and performance needs and that our consensus protocol outperforms the existing proof of work (PoW) and proof of stake (PoS) methods in this application.

Synchronous Circuit Design With Beyond-CMOS Magnetoelectric Spin–Orbit Devices Toward 100-mV Logic

The supply voltage scaling has become increasingly challenging in the advanced CMOS technology due to the threshold voltage requirement for transistor OFF leakage, limiting the system energy efficiency. Spintronic logic utilizes the physical quantity of magnetization or spin as a computation variable, offering new design paradigms in terms of ultralow voltage operation and nonvolatility, but suffering from switching inefficiency of the charge-to-spin conversion. The magnetoelectric spin–orbit (MESO) device has been proposed as a new alternative logic device candidate to solve these issues by magnetoelectric transduction using a novel multiferroic oxide [both ferroelectric (FE) and antiferromagnetic], a ferromagnet and a spin injection layer. It enables a path toward 10–100 $\times $ switching energy reduction compared to CMOS inverter in 2018 node, due to the device and material innovations of a novel switching mechanism. In this paper, in order to build a MESO logic family for new circuit and architecture exploration, we propose for the first time the fundamental building blocks such as MESO sequential and combinatorial circuits for the synchronous logic operation. We employ a transistor sharing and a novel multiphase clocking scheme to address the circuit design issues such as clock control, directionality of state propagation, and power gating and enable the design exploration for MESO digital logic. Based on the proposed circuit techniques, we demonstrate these MESO logic functions operating at a supply voltage of 100 mV and a clock period of 1.2 ns with 320-ac FE polarization through the circuit simulations.

An Improved Storage-Space Selection Model and Algorithm for Outbound Shipping Containers: Considering the Synchronous Operation of Multiple Gantry Cranes in Port Terminals Worldwide

ABSTRACT Zheng, S.; Sha, J., Wang, A., 2019. An improved storage-space selection model and algorithm for outbound shipping containers: Considering the synchronous operation of multiple gantry crane...

A Nanosecond Pulsed Generator With Fast-Solid-State Switch for Synchronous Discharge in Plasma Synthetic Jet Actuators

The plasma produced by a pulsed generator is an efficient tool for an airflow control. In this paper, a nanosecond pulsed generator constructed with a fast solid-state switch is designed for triggering synchronous discharges in plasma synthetic jet (PSJ) actuators connected in series. The generator delivers high-voltage pulses with a peak voltage varying from 0 to 20 kV, a rise time of 20 ns, a full-width at half-maximum of 200 ns, and a wide range of pulse-repetition rate varying from 0 to 5.5 kHz. It is proved that this generator is able to trigger synchronous discharges in three PSJ actuators in atmospheric air with a peak discharge current more than 90 A and a deposited energy per pulse of 39 mJ. A schlieren system is used to observe the airflow dynamics, which shows the high synchronization among the three PSJ actuators with a time triggering delay of about 20 ns. The synchronous operation of three PSJ actuators produces a plasma jet with a maximum velocity of 60 m/s and a precursor wave with a velocity of 350 m/s.

Study on Synchronization of Air-Core Compensated Pulsed Alternator Pairs

As a pulsed power supply, compensated pulsed alternator (CPA) has high power density and high energy density. In order to compensate the torque and gyroscopic effects during the discharge process and improve the ability of power supply, even number of similar counter-rotating alternators could be used, synchronously running in pairs and connecting in parallel to the load. However, there are unavoidable differences in parameters between machines, and this may result in a large difference between their discharge depth and discharge current waveforms and then cause the loss of life of some machines and rectifier devices as well as the decline of system output. Focusing on the synchronization of CPAs running in pairs, the factors that affect the synchronous operation of the machines are analyzed first. Then, the principle and characteristics of using different excitation circuit topologies to achieve synchronization are studied, and the limitations of such methods are pointed out. Finally, three active synchronization methods are proposed: excitation loop suppression (ELS), startup time regulation , and seed capacitor voltage regulation , hoping to make that the discharge depth tends to be the same and the difference of the discharge current amplitude to be in a small range. Simulation results show that all the three methods have good synchronization effect, and the effect of ELS is the best.

Flowshop scheduling problem with parallel semi-lines and final synchronization operation

This paper deals with a particular variant of the flowshop scheduling problem motivated by a real case configuration issued from an electro-electronic material industry. The shop floor environment is composed of two parallel semi-lines and a final synchronization operation. The jobs must follow the same technological order through the machines on each parallel semi-line. However, the operations on each semi-line are independent. The final synchronization operation, operated by a dedicated machine, can only start when the job is finished on both semi-lines. The objective is to determine a schedule that minimizes the makespan for a given set of jobs. Since this problem class is NP-hard in the strong sense, constructive heuristic procedures and metaheuristics methods are introduced to achieve optimal or near-optimal solutions. The performances of the proposed GRASP and the Simulated Annealing algorithms are evaluated and compared with the adaptation of two well-known heuristics. Computational experiments show that the proposed metaheuristics provide very good results in low computational times.

Self-synchronization characteristics of a class of nonlinear vibration system with asymmetrical hysteresis

The self-synchronization characteristics of the two excited motors for the nonlinear vibration system with the asymmetrical hysteresis have been proposed in the exceptional circumstances of cutting off the power supply of one of the two excited motors. From the point of view of the hysteretic characteristics with the asymmetry, a class of nonlinear dynamic model of the self-synchronous vibrating system is presented for the analysis of the hysteretic characteristics of the soil, which is induced by the relation between the stress and the strain in the soil. The periodic solutions for the self-synchronous system with the asymmetrical hysteresis are investigated using nonlinear asymptotic method. The synchronization condition for the self-synchronous vibrating pile system with the asymmetrical hysteresis is theoretical analyzed using the rotor–rotation equations of the two excited motors. The synchronization stability condition also is theoretical analyzed using Jacobi matrix of the phase difference equation of the two excited motors. Using Matlab/Simlink, the synchronous operation of the two excited motors and the synchronous stability operation of the self-synchronous system with the asymmetrical hysteresis are analyzed through the selected parameters. Various synchronous phenomena are obtained through the difference rates of the two excited motors, including the different initial phase and the different initial angular velocity, and so on. Especially, when there is a certain difference in the two excited motors, the synchronous operation of the two excited motors and the synchronous stability operation of the self-synchronous vibrating system with the asymmetrical hysteresis can still be achieved after the power supply of one of the two excited motors has been disconnected. It has been shown that the research results can provide a theoretical basis for the research of the vibration synchronization theory.

A true random number generator architecture based on a reduced number of FPGA primitives

This paper reports on the design, realization and characterization of a True Random Number Generator (TRNG) that operates using as seeds of entropy, the jitter and the metastability introduced by primitives of a Field Programmable Gate Arrays (FPGA) board. In particular, the TRNG architecture has been implemented on a Xilinx Ultrascale XCKU040 FPGA board. Generally, the implementations on FPGA of fully-digital TRNGs make use of ring oscillators employing a large number of Look-Up-Table (LUT) blocks. Differently from this approach, this paper demonstrates that a reliable FPGA-based TRNG architecture can be realized mainly employing only a single PLL and three on-board primitives together with other few basic logic elements (i.e., 8 D-type Flip-Flop, 17 LUT and 2 Counters) used only for the initial overall system synchronization and post-processing operations. In this way, the proposed solution largely reduces the employed number of the FPGA Configurable Logic Blocks (CLB), the circuitry complexity and the overall power consumption without affecting the achievable output bit rate so resulting suitable for full-custom VLSI implementations. The random and statistical properties of the generated 100 Mbps output bitstreams have been validated by passing all the National Institute of Standards and Technology (NIST) tests as well as the Anderson-Darling and the Kolmogorov-Smirnov tests so demonstrating that the proposed TRNG architecture can be suitably employed in security/cybersecurity network systems as well as, once integrated, in Internet-of-Things (IoT) and Industrial-Internet-of-Things (IIoT) applications.

Automatic Synchronizer of Digital Signals and Telecommunication Streams

—The paper proposes a principle of constructing an automatic digital synchronizer of digital or bit data stream from the primary reference oscillator of frequency generating equipment of telecommunication network without the transfer of synchronizing signals from the network reference oscillator. This principle can be used in optical transport networks (OTN), cable channels and in 5G radio relay networks (10–100 Gbit/s). Automatic digital synchronizer enables us to receive asynchronous signals in synchronous mode (RS 232C, CAN) maintaining the synchronous operation of computer or telecommunication network with complete elimination of wander and significant reduction of jitter.

Optimization of Clock Synchronization System Architecture in Nuclear Power Plant

Clock Synchronization System (CSS) can generate standard time, time and frequency signals, and provide various high-precision time reference signals for systems and equipment requiring standard time scale in nuclear power plants. With the rapid development of power system, the requirement of time synchronization is becoming more and more urgent, which requires accurate, safe and reliable clock sources. The structure of nuclear power plant clock synchronization system is constantly optimized to meet the requirements of time synchronization of various systems and equipment, to ensure the time consistency of real-time data acquisition, to improve reliability and to adapt to the interconnection of large power grids in China. At the same time, the interconnection between time synchronization system and time-service equipment or system, and the interconnection of first-level time synchronization system network and operation mode of time synchronization devices from different manufacturers are standard

FPGA Based Real-Time Emulation System for Power Electronics Converters

This paper deals with an emulation system for Power Electronics Converters (PEC). The emulation of PECs is performed on a Field-Programmable Gate Array (FPGA) capable of hard real-time operation. To obtain such a system, the converter operation is described using a differential equations-based model designed with the graph theory. Differential equation coefficients are changed according to the type of converter and pulse-width modulation (PWM) signals. The tie-set and incidence matrix approach for the converter modelling is performed to describe the converter operation in a general way. Such approach enables that any type of PECs can be described appropriately. The emulator was verified experimentally by synchronous operation with a real DC-AC converter built for this purposes.

Research on scheduling of synchronized handling operation of Railway Container Terminals

As an important node of container transportation, the handling efficiency of railway container terminals has a direct impact on the capacity and efficiency of transportation process. In this paper, orbital container gantry crane’s scheduling optimization problem is studied. By research the operation characteristics of gantry crane, considering various constraints, and aiming at the shortest total handling time, an optimization model of synchronous handling operation scheduling is established for improve the efficiency of handling operation at the railway container terminals.

Focus on test, measurement, and data acquisition

Focus on test, measurement, and data acquisition

Design and analysis of improved second order generalized integrator‐based voltage and frequency controller for permanent magnet synchronous generator operating in small‐hydro system feeding single‐phase loads

Design and analysis of improved second order generalized integrator‐based voltage and frequency controller for permanent magnet synchronous generator operating in small‐hydro system feeding single‐phase loads

A Discreet Mathematical Model Based on the Bilinear Transformation of a Synchronous Electric Machine with a Turn-to-Turn Fault in the Rotor Winding

A number of requirements are imposed upon the group of promising discrete mathematical models: a small sampling interval, the guaranteed asymptotic (Lyapunov) stability, explicit nature of numerical methods, and program and algorithmic optimization of calculations. The application of bilinear transformation to construct a discrete mathematical model of a synchronous electric machine with a turn-to-turn fault of the rotor winding is considered. This approach makes it possible to tackle a number of problems which arise when standard methods for solving a Cauchy problem are used—namely, nonstationarity of dynamical systems and influence of the integration error on the accuracy. A transfer from a system of differential equations, describing the physics of synchronous generator operation, to difference equations is considered. Based on the difference equations obtained, a structural scheme is composed which allows the mathematical model software to be implemented on the microcontroller without involving additional mathematical functions. The experimental testing of adequacy of the discrete mathematical model of a synchronous generator with a turn-to-turn fault is performed. The proposed approach can be used to solve problems on identification of turn-to-turn faults, where an adequate high-speed and stable model is necessary.